Images binding: allow setting headers on .response()

[Monark-Arkmon]

response() now accepts an optional headers option, so you can set Cache-Control (or anything else) without manually rebuilding the Response:

result.response({
  headers: { 'Cache-Control': 'public, max-age=3600, stale-while-revalidate=86400' },
});

content-type is always taken from the transformed image and can't be overridden by a header you pass in.

This pairs nicely with Workers Cache - now that Cache-Control on the response is all you need to get a transform cached at the edge, it was a bit annoying to have to hand-roll headers just to set that one thing.

[ns476]

LGTM ✅